http://hdl.handle.net/11422/86 Tue, 07 Apr 2026 19:10:23 GMT 2026-04-07T19:10:23Z http://hdl.handle.net/11422/28742 Title: Análise de sensibilidade de um método expedito para avaliação dos esforços de tração em linhas de ancoragem Author(s)/Inventor(s): Ribeiro, Caio Lucas Nascimento Advisor: Sagrilo, Luis Volnei Sudati Abstract: Recently, accidents in floating units caused by structural failure of mooring lines have drawn the attention of the oil and gas industry. These events have significantly increased the need for continuous monitoring of the structural integrity of mooring lines, which has fueled the demand for reliable and computationally inexpensive methods for obtaining the tension responses over time in these lines. Among the various methods available for obtaining these time series, two stand out as the most common: the first is a quasi-static approach, which consists of a simplified analysis using only the catenary equation; and the second, through the Finite Element Method (FEM), using tri-dimensions non-linear bar elements. The catenary equation is commonly used for evaluating tension in cables due to its low computational cost. However, this method does not consider the effects of damping and inertia in the lines. On the other hand, the FEM considers the effects of damping and inertia to obtain the forces over time but has a higher computational cost. This work aims to investigate the use of a method that combines high accuracy with low computational cost, thus providing a reliable and computationally inexpensive evaluation of the tension response of mooring lines. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Sat, 01 Jun 2024 00:00:00 GMT http://hdl.handle.net/11422/28742 2024-06-01T00:00:00Z http://hdl.handle.net/11422/28741 Title: Caracterização faciológica de rochas carbonáticas e suas classes texturais em imagens de tomografia computadorizada associadas ao sistema permoporoso: uma abordagem aplicada às rochas do Pré-sal da Bacia de Santos Author(s)/Inventor(s): Barboza, Ana Carolina Carius Lisboa Advisor: Landau, Luiz Abstract: The Santos Basin holds significant economic potential due to the extensive carbonate reservoirs of lacustrine origin in the Pre-salt. However, uncertainties persist regarding the lacustrine carbonate rocks of the Brazilian Pre-salt, due to the lack of analogous outcrops and the variability caused by diagenetic processes. Identifying the main lithological deposits, recognizing textural attributes in X-ray computed tomography (CT) images, and understanding the permoporous system of these rocks are geologically intriguing challenges. This research aims to define the main textures through CT images of lacustrine carbonate rock cores from the Barra Velha Formation in an oil field in the Santos Basin, and to understand the permoporosity behavior of each textural class to identify potential reservoirs. The methodology involved four stages: detailed geological characterization, permoporosity characterization, definition of the main textures in CT images, and analysis of the relationship between textures, lithofacies, and permo-porous systems. Six lithofacies and a textural classification with four classes were identified: laminated, bushy, nodular, and recrystallized, with a direct influence of advanced diagenetic processes on two textures and their permo-porous systems. This textural classification of lacustrine carbonate rocks from the Barra Velha Formation is effective in identifying features of interest for reservoirs and can be used by a specialist technician as a basis for training machine learning algorithms. Publisher: Universidade Federal do Rio de Janeiro Type: Tese Mon, 01 Apr 2024 00:00:00 GMT http://hdl.handle.net/11422/28741 2024-04-01T00:00:00Z http://hdl.handle.net/11422/28383 Title: Wave energy resource assessment near Guanabara bay, Rio de Janeiro, Brazil Author(s)/Inventor(s): Campos, Rafael Vieira Advisor: Landau, Luiz Abstract: Having the 1973 oil crisis as a warning, the developments in technologies related to renewable energy have increased significantly over the years. Wind-generated waves in the ocean offer a renewable energy resource and can be predicted several days in advance. However, they must be well-evaluated to optimize their exploitation. The present study uses numerical modeling to assess wave energy resources near Guanabara Bay in Rio de Janeiro. We developed a hindcast system consisting of two spectral wave models to simulate two years of wave scenarios, 2017 and 2018. The global wave model WAVEWATCH III was run with four nested computation grids. The lower grid provided boundary conditions for the regional wave model SWAN, which has a computational grid of 100 meters of resolution. The spatial and temporal wave energy distribution was studied considering the monthly, seasonal, and annual averages. The results were evaluated based on measured data from two meteoceanographic buoys. Furthermore, the root mean square error (RMSE), bias, scatter index (SI), symmetric slope (sym r), and correlation coefficient (corr) were applied as evaluation methods. The average wave energy for the annual time scale was similar between 2017 and 2018, reaching 8 kW / m near the Ilha Redonda island and 5 kW/m at the bay entrance. However, the results of the SV index suggest a significant difference between the seasonal variability of both years. The validation results show values for the bias equal to -0.20224 for the RJ-3 buoy and -0.08948 for the RJ-4 buoy. Therefore, the study area presents itself as promising in wave energy generation. However, seasonal variability should be a concern when selecting wave energy converters. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Thu, 01 Dec 2022 00:00:00 GMT http://hdl.handle.net/11422/28383 2022-12-01T00:00:00Z http://hdl.handle.net/11422/28382 Title: Estudo da influência da variação de umidade pós compactação no comportamento mecânico de três solos típicos de subleitos rodoviários brasileiros Author(s)/Inventor(s): Oliveira, Nivalda Aparecida Condé de Advisor: Motta, Laura Maria Goretti da Abstract: This work evaluates the influence of the variation of post-compaction humidity and of the suction in the mechanical behavior of three soils, through triaxial tests of repeated loads. The tests were carried out on specimens compacted at optimal humidity and subsequently submitted to saturation or air drying. In order to evaluate the suction, the retention curves were determined through tests carried out in the HYPROP and Richards Extractor equipment’s. Additionally, with the results obtained, simulations were performed in the MeDiNa program in order to evaluate the effects of post-compaction moisture variation on pavement design. It was found that air drying caused a small reduction in permanent deformations, while saturation produced a significant increase, contrary to the behavior observed for the resilience modulus tests. In addition, it was found that with the addition of suction, the resilience modulus increases and the permanent deformation decreases. In the design of pavements, it was observed that the addition of post-compaction humidity can make a pavement, designed with parameters obtained in the optimal humidity, reach the percentage of cracked area and/or maximum wheel track sinking recommended by the program before the end of its useful life. Furthermore, this work contributed to the expansion of the database of the MeDiNa program, mainly by incorporating humidity conditions different from the optimum Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação Tue, 01 Mar 2022 00:00:00 GMT http://hdl.handle.net/11422/28382 2022-03-01T00:00:00Z